In order to counteract the deleterious effects of gravity, poor posture or excessive weight on the spine, and in order to provide treatment for various disorders of the spine, therapists and doctors have used specially designed tables to generate intersegmental traction on the spine, by imposing motion on the various anatomical segments of the spine. In this way, pressure on spinal nerves may be relieved, and the flow of spinal fluid in the spinal column and of blood in the musculature and other tissues adjacent to or overlying the spine may be increased.
It is known to provide such massage or treatment tables that include roller assemblies that are designed to contact at least a portion of the spine of a patient and apply rolling pressure thereto. Most of these devices employ a plurality of rollers, all of the same size, for applying pressure to various areas of the spine. Some, such as those of U.S. Pat. No. 5,088,475 of Steffensmeier, U.S. Pat. No. 3,687,133 of Grubelic and U.S. Pat. No. 2,909,173 of Anderson, include a plurality of rollers that are mounted on a carriage that moves back and forth along the spine of a patient beneath the top surface of a table on which the patient is reclining. Others, such as those of U.S. Pat. No. 4,190,043 of Thompson, U.S. Pat. No. 4,154,232 of Fukazawa and U.S. Pat. No. 3,830,233 of Hill, include a reciprocating table top that moves a patient back and forth above a roller assembly. In some of these known massage tables, the rollers may also be mounted on a support that pivots about a point on a fixed frame or on the moving carriage. Thus for example, the Steffensmeier table includes three pairs of tandem rollers of the same size that are rotatably mounted on a common support plate that is also rotated about a central axis on the carriage as it travels along a track from one end of the table to the other. The Thompson table also includes three rollers of the same size that are mounted on a common support plate like that of Steffensmeier. The Thompson support plate is rotated about a central drive shaft, so that the rollers sequentially contact the patient who is moving back and forth on the reciprocating table top. Each of the rollers in these devices will contact a portion of the spine as the rollers and the patient move with respect to each other. All of these devices require a complicated reciprocating mechanism of some sort, either to move a roller assembly beneath a reclining patient or to move the patient above a roller assembly.
Other known devices, such as those of U.S. Pat. No. 4,011,862 of Kosiak and U.S. Pat. No. 3,523,524 of Wilson, include an endless belt or conveyor which carries a number of rollers of the same size along a track beneath a table top so that the rollers move along the spine of the patient that is exposed by the table top. However, these conveyor-type devices are complicated mechanisms that are expensive to build and operate and more likely to be subject to mechanical failure than is a simpler device.
Most of the known massage or treatment tables operate by urging the rollers upwardly in a uniform manner along the length of the spine of the reclining patient. Many of these tables employ rollers having the same diameter and curvature for contact with all regions or areas of the patient's spine. However, the presentation of a constant force at the upper surface of the treatment table will not generally result in the application of a consistent therapeutic force to the various areas of the spine of the patient reclining thereon, because the human spine is not straight, even when the patient is reclining on a table. The normal spine exhibits a nearly "S" shaped physiological curvature, lordotic in the lumbar and cervical regions and kyphotic in the thoracic region. Because of this normal curvature, the spine of a patient reclining on a table will likely be in intimate contact with the surface of the table in the thoracic region, but will likely arch away from the surface in the lumbar and cervical regions. Therefore, the known tables do not adequately apply the same massage or therapeutic pressure with the rollers to all regions of the spine. If the rollers are sized and mounted so as to apply appropriate pressure to the lumbar portion of the patient's spine, for example, they may apply too great a pressure to the thoracic portion, causing the patient to experience discomfort or pain as a roller passes over the thoracic portion. On the other hand, if the rollers are appropriately size and mounted to apply effective pressure to the thoracic portion of the spine, for example, they may not apply sufficient pressure to the lumbar portion.
The Grubelic and Fukazawa devices attempt to compensate for this deficiency by providing a suspended flexible platform on which the patient may recline. However, the Grubelic device employs a complicated arrangement of rocker arms carrying pairs of rollers at each end to apply pressure at various points along the spine of the patient. The Fukazawa device suspends the platform from each end in the manner of a hammock above eccentrically rotated rollers that slide as they rotate in contact with the lower side of the hammock. Because the Fukazawa rollers both slide and rotate, the massaging force applied to each particular area of the spine is varied between a strong and a weakened force as the treatment progresses.
The Wilson and Kosiak devices attempt to apply uniform pressure by curving the track of the conveyor carrying the rollers to match the curvature of the patient's spine. The curvature of the Wilson track is adjustable to match the spinal curvature of an individual patient, but adjustment of this device requires the adjustment of a number of vertical adjusting rods to which the track is affixed. This is a time-consuming process and may be difficult to accomplish in an efficient manner.
It is apparent that many of the known therapeutic massage tables suffer from the inability to apply an anatomically adjusted or therapeutically consistent rolling force or pressure to the various regions of the spine. Many of the known devices are also complicated structures that are expensive to build and operate and more likely to be subject to mechanical breakdown.